Question

Lab 7

Define Osmosis -
What happens to Animal/ Plant cells in these environments: Isotonic -
Hypertonic -
Hypotonic -

Define:
Natural Selection - Evolution - Directional Selection - Allele -

Answer 1

Osmosis- is the process of movement of solvent molecules from a less concentrated solution to a highly concentrated solution through a semipermeable membrane. the movement of solvent will continue till the concentration of two solutions become equal.

When an animal/plant cell is placed in an isotonic solution, no net gain or loss of water occur. ie the cell will remain as such and maintain its shape. (Isotonic solutions are solutions with equal amount of dissolved salts)

When an animal/plant cell is placed in an hypertonic solution, the cell will loose its water and the cell will shrink.

When an animal/plant cell is placed in an hypotonic solution, the cell will absorb more water through the plasma membrane into the cell. As a result the cell will enlarge and sometimes it will burst.

Solution type	Effect on cells
Isotonic solution	Cell maintains it shape
Hypertonic solution	Cell shrinks
Hypotonic solution	Cell enlarges

Natural selection-is the process of selection of better adapted individuals by the nature. Survival of organisms which are better adapted to the environmental conditions and produce more offsprings are favored by the nature. the theory of natural selection was put forward by Charls Darwin

Evolution- is the process of change in heritable characteristics and formation of a new species from an ancestor organism. Eg. Evolution of Homo sapiens (Humans) from Homo erectus

Directional selection- It is the selection of individuals with extreme phenotypes. It is also called positive selection. Here the environment favor a particular phenotype over all the other phenotypes. Eg. Shift in color of peppered moth from light color to dark during the industrial revolution. Pollution due to industrialization favored dark colored moths

Allele- Alleles are alternate forms of genes. One gene may be represented by more than two alleles. Eg. Blood group (ABO) in humans is caused by multiple alleles.